Anthrax vaccine

ABSTRACT

Using the nontoxic PA protein from  B. anthracis , a method and composition for use in inducing an immune response which is protective against anthrax in subjects is described.

This application claims the benefit of Provisional application Ser. No. 60/092,416 filed Jul. 10, 1998.

FIELD OF THE INVENTION

This invention relates to vaccines for bacterial toxins from Bacillus anthracis.

INTRODUCTION

Anthrax is a disease cause by the sporulating bacteria Bacillus anthracis. Humans working with animal products are at risk from contracting anthrax. Areas such as Iran, Turkey, Iraq, Pakistan, and sub-Saharan Africa are hyperendemic for anthrax, although the organism can be found in most areas of the world. Anthrax manifests disease in three different ways. Inhalation, gastrointestinal, and cutaneous anthrax result from inhaling spores, ingesting spores in contaminated meat, or contacting spores in an open wound, respectively. Untreated inhalation or gastrointestinal anthrax has a case fatality rate of essentially 100 percent while cutaneous anthrax has a case fatality rate of up to 25 percent. Previous research has shown that the protective antigen (PA) produced by B. anthracis can protect mice from anthrax. Even though the Anthrax vaccine is FDA licensed, reactogenicity is mild to moderate.

Therefore, there is a need for an efficacious vaccine for anthrax useful for protecting humans.

SUMMARY OF THE INVENTION

The present invention satisfies the need discussed above. The present invention relates to a method and composition for use in inducing an immune response which is protective against infection with anthrax.

In this vaccine strategy, a gene coding for a protein of interest is cloned into a VEE virus vector in place of the VEE virus structural genes; the result is a self-replicating RNA molecule, a replicon, that encodes its own replicase and transcriptase functions, and in addition makes abundant quantities of mRNA encoding the foreign protein. When replicon RNA is transfected into eukaryotic cells along with two helper RNAs that express the VEE structural proteins (glycoproteins and nucleocapsid), the replicon RNA is packaged into VEE virus-like particles by the VEE virus structural proteins, which are provided in trans. Since the helper RNAs lack packaging signals neccessary for further propagation, the resulting VEE replicon particles (VRPs) which are produced are infectious for one cycle but are defective thereafter. Upon infection of an individual cell with a VRP, an abortive infection occurs in which the infected cell produces the protein of interest in abundance, is ultimately killed by the infection, but does not produce any viral progeny (Pushko et al., 1997, Virology 239, 389-401).

The PA gene which contains a prokaryotic secretory signal and the entire 83 kDa coding sequence (Welkos et al., 1988, Gene 69, 287-300), was inserted into the VEE replicon vaccine vector (FIG. 1) and have demonstrated high level expression of this bacterial protein in eukaryotic cells in culture. Mice, either the C57BL/6 strain or the A/J strain, inoculated with VRP containing the PA-replicon produced high specific antibody titers and were protected from developing anthrax when challenged subcutaneously with B. anthracis.

Therefore, it is one object of the present invention to provide a VEE virus replicon vector comprising a VEE virus replicon and DNA fragments encoding the PA protein from B. anthracis.

It is another object of the present invention to provide a self replicating RNA comprising the VEE virus replicon and any of the B. anthracis fragments described above.

It is another object of the present invention to provide infectious VEE virus replicon particles produced from the VEE virus replicon RNA described above.

It is further an object of the invention to provide an immunological composition for the protection of mammals against B. anthracis infection comprising VEE virus replicon particles containing any of the B. anthracis fragments described above or a combination of different VEE virus replicons each having a different B. anthracis fragment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims, and accompanying drawings where:

FIG. 1. Diagram of the protective antigen (PA) replicon constructs. The PA replicons are similar to the full-length VEE RNA except that the open reading frame encoding the VEE structural proteins was replaced with the PA genes.

FIG. 2. Western blot of BHK cell lysates showing expression of anthrax protective antigen from recombinant VEE replicons. a) uninfected cell lysate; b) recombinant expression product from B. anthracis; c) infected cell lysate.

FIGS. 3A and 3B. ELISA titers for mice (A, C57Bl/6 mice; B, A/J mice) immunized with PA-VRP. GMTs only includes those mice that survived challenge. a) Received 0.2 ml on day 0 and 28. b) Received 10⁷ iu on day 0 and 28. c) Received 10⁷ iu PA-VRP on day 0, 28, 56, and 84; C57Bl/6 mice that died, titer=100; A/J mice that died, titer=400. d) Received 10⁷ iu PA-VRP on day 0, 28, and 56; C57Bl/6 mice that died, titers=400, 100, 100; A/J mice that died, titers=102400, 100, 1600. e) Received 10⁷ iu PA-VRP on day 0, and 28; C57Bl/6 mice that died, GMT=1313; A/J mice that died, GMT=1766. Mice were challenged 28 days after last inoculation with 18-32 LD₅₀ Sterne strain for C57Bl/6 and 12-25 LD₅₀ Sterne strain for A/J mice.

FIG. 4. Schematic representation of constructs containig PA.

DETAILED DESCRIPTION

In the description that follows, a number of terms used in recombinant DNA, virology and immunology are extensively utilized. In order to provide a clearer and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided.

Replicon. A replicon is equivalent to a full length virus from which all of the viral structural proteins have been deleted. A multiple cloning site can be cloned into the site previously occupied by the structural protein genes. Virtually any heterologous gene may be cloned into this cloning site. Transcription of the RNA from the replicon yields an RNA capable of initiating infection of the cell identically to that seen with the full-length infectious virus clone. However, in lieu of the viral structural proteins, the heterologous antigen is expressed. This system does not yield any progeny virus particles because there are no viral structural proteins available to package the RNA into particles.

Particles which appear structurally identical to virus particles can be produced by supplying structural proteisn for packaging of the replicon RNA in trans. This is typically done with two helpers also called defective helper RNAs. One helper consists of a full length infectious clone from which the nonstructural protein genes and the glycoprotein genes are deleted. The helper retains only the terminal nucleotide sequences, the promoter for subgenomic mRNA transcription and the sequences for the viral nucleocapsid protein. The second helper is identical to the first except that the nucleocapsid gene is deleted and only the glycoprotein genes are retained. The helper RNA's are transcribed in vitro and co-transfected with replicon RNA. Because the replicon RNA retains the sequences for packaging by the nucleocapsid protein, and because the helpers lack these sequences, only the replicon RNA is packaged by the viral structural proteins and released from the cell. The particles can then by inoculated into animals similar to parent virus. The replicon particles will initiate only a single round of replication because the helpers are absent, they produce no progeny virus particles, and express only the viral nostructural proteins and the product of the heterologous gene cloned in place to the structural proteins.

The VEE virus replicon is a genetically reorganized version of the VEE virus genome in which the structural proteins genes are replaced with a gene from an immunogen of interest, in this invention, the B. anthracis proteins. The result is a self replicating RNA (replicon) that can be packaged into infectious particles using defective helper RNAs that encode the glycoprotein and capsid proteins of the VEE virus.

Subject. Includes both human, animal, e.g., horse, cattle, donkey, monkey, pig, dog, guinea pig, mouse, hamster, avian e.g., chicken, pheasant or turkey, fish and other marine animals, and insects such as mosquito.

In one embodiment, the present invention relates to a recombinant DNA molecule that includes a VEE replicon and a DNA sequence encoding the non-toxic protective antigen (PA) from B. anthracis. The sequence for PA has been determined and has been deposited in GenBank at accession no. M22589. The PA sequence encodes a prokaryotic secretory signal in addition to the entire sequence encoding the 83 Kd PA (SEQ ID NO:1). Other nucleic acid sequences related to this invention include sequences wherein the secretory signal has been removed (MAT-PA)(SEQ ID NO:2), or replaced with other secretory signals known to people in the art such as the tissue plasminogen activator (TPA) secretory signal resulting in a DNA fragment encoding TPA-PA (SEQ ID NO:3). Nucleic acid sequences included in this invention are sequences encoding the active form of PA, a 63 kDa protein, termed PA63 (SEQ ID NO:4). In addition, isolated nucleic acid molecules of the invention include DNA molecules which comprise a sequence substantilly different from those described above but which, due to the degeneracy of the genetic code, still encode the B. anthracis proteins described and specified in SEQ ID NO:5 (TPA-PA), SEQ ID NO:6 (PA), SEQ ID NO:7 (MAT-PA), and SEQ ID NO:8 (PA63). Of course, the genetic code and species-specific codon preferences are well known in the art. Thus, it would be routine for one skilled in the art to generate the degenerate variants described above, for instance, to optimize codon expression for a particular host (e.g., change codons in the human mRNA to those preferred by a bacterial host such as E.coli).

Nucleic acid molecules of the present invention may be in the form of RNA, or in the form of DNA, including, for instance, cDNA and genomic DNA obtained by cloning or produced synthetically. The DNA may be double-stranded or single-stranded. Single-stranded DNA or RNA may be the coding strand, also known as the sense strand, or it may be the non-coding strand, also referred to as the antisense strand.

By “isolated” nucleic acid molecule(s) is intended a nucleic acid molecule, DNA or RNA, which has been removed from its native environment. For example, recombinant DNA molecules contained in a vector are considered isolated for the purposes of the present invention. Further examples of isolated DNA molecules include recombinant DNA molecules maintained in heterologous host cells or purified (partially or substantially) DNA molecules in solution. Isolated RNA molecules include in vivo or in vitro RNA transcripts of the DNA molecules of the present invention. Isolated nucleic acid molecules according to the present invention further include such molecules produced synthetically.

The present invention is further directed to nucleic acid molecules encoding portions or fragments of the nucleotide sequences described herein. Fragments include portions of the nucleotide sequences of at least 10 contiguous nucleotides in length selected from any two integers, one of which representing a 5′ nucleotide position and a second of which representing a 3′ nucleotide position, where the first nucleotide for each nucleotide sequence is position 1. That is, every combination of a 5′ and 3′ nucleotide position that a fragment at least 10 contiguous nucleotide bases in length or any integer between 10 and the length of an entire nucleotide sequence minus 1.

The present invention further relates to variants of the nucleic acid molecules of the present invention, which encode portions, analogs or derivatives of the B. anthracis polypeptides described above. Variants may occur naturally, such as a natural allelic variant. By an “allelic variant” is intended one of several alternate forms of a gene. occupying a given locus of a chromosome of an organism. Non-naturally occuring variants may be produced by known mutagenesis techniques. Such variants include those produced by nucleotide substitution, deletion, or addition of one or more nucleotides in the coding or noncoding regions or both. Alterations in the coding regions may produce conservative or nonconservative amino acid substitutions, deletions, or additions. Especially preferred among these are silent substitutions, additions, and deletions which do not alter the properties and activities of the B. anthracis polypeptides disclosed herein or portions thereof. Also preferred in this regard are conservative substitutions.

In another embodiment, the present invention relates to a recombinant DNA molecule that includes a vector and a DNA sequence as described above. The vector can take the form of a plasmid, phage, cosmid, YAC, eukaryotic expression vector such as a DNA vector, Pichia pastoris, or a virus vector such as for example, baculovirus vectors, retroviral vectors or adenoviral vectors, and others known in the art. The cloned gene may optionally be placed under the control of (i.e., operably linked to) certain control sequences such as promoter sequences, or sequences which may be inducible and/or cell type-specific. Suitable promoters will be known to a person with ordinary skill in the art. The expression construct will further contain sites for transcription initiation, termination and, in the transcribed region, a ribosome binding site for translation. When the DNA sequences described above are in a replicon expression system, such as the VEE replicon described above, the proteins can be expressed in vivo. The DNA sequence for any of the B. anthracis proteins described above can be cloned into the multiple cloning site of a replicon such that transcription of the RNA from the replicon yields an infectious RNA containing the B. anthracis protein or proteins of interest. Use of helper RNA containing sequences necessary for encapsulation of the viral transcript will result in the production of viral particles containing replicon RNA which are able to infect a host and initiate a single round of replication resulting in the expression of the B. anthracis proteins. Such replicon constructs include those listed in Table 1.

TABLE 1 Replicon Plasmid Name expresses p3014-TPA-PA TPA signal, 5 amino acids of C terminal end of prokaryotic secretory signal, and the 83 kDa mature protein. p3014-PA 29 amino acid prokaryotic secretory signal, and the 83 kDa mature protein secreted by B. anthracis p3014-MAT-PA 83 kDa mature protein p3014-PA63 63 kDa protein (minus 20 kDa N- terminal end that is naturally cleaved off by furin proteases at host cell membrane surface) p3014-sub-domains subdomain #1: from nucleotide 1891 to 2391; subdomain #2: from nucleotide 2392 to 2658; subdomain #3: from nucleotide 2659 to 3351; subdomain #4: from nucleotide 3352 to 3669; subdomain #5: from nucleotide 3670 to 4098 (Subdomains are numbered according to Welkos et al., 1988, supra, determined on subdomains present in the crystal structure, Petosa, et al., 1997, Nature 385, 833-838).

The VEE constructs containing anthrax proteins can be used as a DNA vaccine, or for the production of RNA molecules as described below.

In another embodiment, the present invention relates to RNA molecules resulting from the transcription of the constructs described above. The RNA molecules can be prepared by in vitro transcription using methods known in the art and described in the Examples below. Alternatively, the RNA molecules can be produced by transcription of the constructs in vivo, and isolating the RNA. These and other methods for obtaining RNA transcripts of the constructs are known in the art. Please see Current Protocols in Molecular Biology. Frederick M. Ausubel et al. (eds.), John Wiley and Sons, Inc. The RNA molecules can be used, for example, as a nucleic acid vaccine, or to transfect cells along with RNA from helper plasmids, one of which expresses VEE glycoproteins and the other VEE capsid proteins, as described above, in order to obtain replicon particles.

Introduction of the construct into the host cell can be effected by calcium phosphate transfection, electroporation, infection, and other methods known in the art and described in standard laboratory manuals such as Current Protocols in Molecular Biology, Ausubel, F. M. et al. (Eds), Wiley & Sons, Inc. All documents cited herein supra and infra are hereby incorporated in their-entirety by reference thereto.

In a further embodiment, the present invention relates to host cells stably transformed or transfected with the above-described recombinant DNA constructs. The host cell can be prokaryotic (for example, bacterial), lower eukaryotic (for example, yeast or insect) or higher eukaryotic (for example, all mammals, including but not limited to rat and human). Both prokaryotic and eukaryotic host cells may be used for expression of desired coding sequences when appropriate control sequences which are compatible with the designated host are used. Among prokaryotic hosts, E. coli is most frequently used. Expression control sequences for prokaryotes include promoters, optionally containing operator portions, and ribosome binding sites. Transfer vectors compatible with prokaryotic hosts are commonly derived from, for example, pBR322, a plasmid containing operons conferring ampicillin and tetracycline resistance, and the various pUC vectors, which also contain sequences conferring antibiotic resistance markers. These markers may be used to obtain successful transformants by selection. Please see e.g., Maniatis, Fitsch and Sambrook, Molecular Cloning; A Laboratory Manual (1982) or DNA Cloning, Volumes I and II (D. N. Glover ed. 1985) for general cloning methods. The DNA sequence can be present in the vector operably linked to a sequence encoding an IgG molecule, an adjuvant, a carrier, or an agent for aid in purification of protein of the invention, such as glutathione S-transferase. The recombinant molecule can be suitable for transfecting eukaryotic cells, for example, mammalian cells and yeast cells in culture systems. Saccharomzyces cerevisiae, Saccharomyces carlsbergensis, and Pichia pastoris are the most commonly used yeast hosts, and are convenient fungal hosts. Control sequences for yeast vectors are known in the art. Mammalian cell lines available as hosts for expression are known in the art and include many immortalized cell lines available from the American Type Culture Collection (ATCC), such as baby hamster kidney (BHK) cells, MRC-5 cells and vero cells, to name a few. Suitable promoters are also known in the art and include viral promoters such as that from SV40, Rous sarcoma virus (RSV), adenovirus (ADV), bovine papilloma virus (BPV), and cytomegalovirus (CMV). Mammalian cells may also require terminator sequences and poly A addition sequences; enhancer sequences which increase expression may also be included, and sequences which cause amplification of the gene-may also be desirable. These sequences are known in the art. The transformed or transfected host cells can be used as a source of DNA sequences described above. When the recombinant molecule takes the form of an expression system, the transformed or transfected cells can be used as a source of the protein or polypeptide specified as amino acid sequence in SEQ ID NO:5 (TPA-PA), SEQ ID NO:6 (PA), SEQ ID>NO:7 (MAT-PA), and SEQ ID NO:8 (PA63).

A polypeptide or amino acid sequence derived from the amino acid sequences mentioned above, refers to a polypeptide having an amino acid sequence identical to that of a polypeptide encoded in the sequence, or a portion thereof wherein the portion consists of at least 2-5 amino acids, and more preferably at least 8-10 amino acids, and even more preferably at least 11-15 amino acids, or which is immunologically identifiable with a polypeptide encoded in the sequence.

A recombinant or derived polypeptide is not necessarily translated from a designated nucleic acid sequence; it may be generated in any manner, including for example, chemical synthesis, or expression of a recombinant expression system. In addition the polypeptide can be fused to other proteins or polypeptides which increase its antigenicity, such as adjuvants for example.

The recombinant or fusion protein can be used as a vaccine for immunity against anthrax infection or as a diagnostic tool for detection of bacillus anthracis. The transformed host cells can be used to analyze the effectiveness of drugs and agents which inhibit anthrax or B. anthracis proteins, such as host proteins or chemically derived agents or other proteins which may interact with B. anthracis proteins of the present invention to inhibit its function. A method for testing the effectiveness of an anti-anthrax drug or agent can for example be the rat anthrax toxin assay (Ivins et al. 1984, Infec. Immun. 52, 454-458 and Ivins et al. 1986) or a skin test in rabbits for assaying antiserum against anthrax toxin (Belton and Henderson, 1956, Br. J. Exp. Path. 37, 156-160).

In another embodiment, the present-invention relates to an anthrax vaccine comprising one or more replicon particles derived from one or more replicons encoding one or more B. anthracis proteins or polypeptides as described above. The present invention relates a method for providing immunity against anthrax said method comprising administering one or more replicon particles containing any combination of the B. anthracis proteins to a subject such that a protective immune reaction is generated.

Vaccine formulations of the present invention comprise an immunogenic amount of a replicon particle, resulting from one of the replicon constructs described above, or a combination of replicon particles as a multivalent vaccine, in combination with a pharmaceutically acceptable carrier. An “immunogenic amount” is an amount of the replicon particles sufficient to evoke an immune response in the subject to which the vaccine is administered. An amount of from about 10² to 10⁷ per dose is suitable, more or less can be used depending upon the age and species of the subject being treated. Exemplary pharmaceutically acceptable carriers include, but are not limited to, sterile pyrogen-free water and sterile pyrogen-free physiological saline solution.

Administration of the replicon particles disclosed herein may be carried out by any suitable means, including both parenteral injection (such as intraperitoneal, subcutaneous, or intramuscular injection), by in ovo injection in birds, orally and by topical application of the virus (typically carried in the pharmaceutical formulation) to an airway surface. Topical application of the virus to an airway surface can be carried out by intranasal administration (e.g. by use of dropper, swab, or inhaler which deposits a pharmaceutical formulation intranasally). Topical application of the virus to an airway surface can also be carried out by inhalation administration, such as by creating respirable particles of a pharmaceutical formulation (including both solid particles and liquid particles) containing the replicon as an aerosol suspension, and then causing the subject to inhale the respirable particles. Methods and apparatus for administering respirable particles of pharmaceutical formulations are well known, and any conventional technique can be employed. An “immunogenic amount” is an amount of the replicon particles sufficient to evoke an immune response in the subject to which the vaccine is administered.

When the replicon RNA or DNA is used as a vaccine, the replicon RNA or DNA can be administered directly using techniques such as delivery on gold beads (gene gun), delivery by liposomes, or direct injection, among other methods known to people in the art. Any one or more constructs or replicating RNA described above can be use in any combination effective to elicit an immunogenic response in a subject. Generally, the nucleic acid vaccine administered may be in an amount of about 1-5 ug of nucleic acid per dose and will depend on the subject to be treated, capacity of the subject's immune system to develop the desired immune response, and the degree of protection desired. Precise amounts of the vaccine to be administered may depend on the judgement of the practitioner and may be peculiar to each subject and antigen.

The vaccine may be given in a single dose schedule, or preferably a multiple dose schedule in which a primary course of vaccination may be with 1-10 separate doses, followed by other doses given at subsequent time intervals required to maintain and or reinforce the immune response, for example, at 1-4 months for a second dose, and if needed, a subsequent dose(s) after several months. Examples of suitable immunization schedules include: (i) 0, 1 months and 6 months, (ii) 0, 7 days and 1 month, (iii) 0 and 1 month, (iv) 0 and 6 months, or other schedules sufficient to elicit the desired immune responses expected to confer protective immunity, or reduce disease symptoms, or reduce severity of disease.

The following MATERIALS AND METHODS were used in the examples that follow.

Plasmids. Construction of the VEE replicon, capsid (C-) helper, and glycoprotein (GP-) helper plasmids was previously described (Pushko, 1997, supra). The PA gene from nucleotide 1804 to 4098 (SEQ ID NO:1) (Welkos et al., 1988, supra) was cloned into the VEE replicon plasmid as a BamHI/BamHI fragment utilizing a shuttle vector. TPA-PA (SEQ ID NO:3), MAT-PA (SEQ ID NO:2), and PA63 (SEQ ID NO:4) were PCR amplified using forward and reverse primers which also contained the ClaI recognition site. The PCR products were agarose gel purified and ligated into the T/A vector pCR2.1 (Invitrogen, Inc.). The PA genes, after digestion of pCR2.1-PA's with ClaI, were ligated into the VEE replicon plasmid. The Lassa nucleocapsid replicon (Lassa N-replicon) was constructed as previously described (Pushko, 1997, supra) and used as a negative control replicon.

Production of VRP. Plasmid templates for the PA-replicons, C-helper, GP-helper, and the Lassa N-replicon were linearized by digestion with NotI at a unique site downstream from the coding sequences, and capped run-off transcripts were prepared in vitro using T7 RNA polymerase. Packaging of the replicons into VEE replicon particles (VRPs) was accomplished by electroporating the replicon RNA and the two helper RNAs into BHK cells. VRPs were harvested between 20 and 27 hours after transfection and purified from cell culture supernatants by ultracentrifugation through a discontinuous sucrose gradient (20%). After reconstituting the pelleted VRP in 1/50 volume phosphate buffered saline, the VRPs were stored at −70° C.

Analysis of expression products and titration of VRP. Subconfluent monolayers were infected with PA-VRP's (either TPA-PA, PA, MAT-PA, or PA63) or Lassa N-VRP (m.o.i.=2) or cell suspensions were electroporated with replicon RNA. Cells were harvested at approximately 20-24 hours and expressed proteins were separated by SDS-PAGE. Visualization of PA proteins was accomplished using a chemiluminescence western blot assay and antibodies specific for each protein. Titration of VRPs was accomplished by infecting subconfluent monolayers with increasing dilutions of purified VRP. Antigen positive cells were visualized in an indirect immunofluorescence assay using a monoclonal antibody specific for each protein, or in a direct immunofluorescence assay using an FITC-conjugated monkey anti-Lassa serum.

Immunization of mice. Mice were inoculated 1 to 4 times at 28 day intervals with 10⁵ to 10⁷ infectious units (iu) of either PA-VRP or Lassa N-VRP (negative control). Positive control mice for the anthrax study were inoculated subcutaneously with 0.2 ml of anthrax vaccine at 28 day intervals. Serum for ELISA was obtained 2 days before each inoculation and 3 days before challenge.

Enzyme-linked immunosorbent assay (ELISA). Microtiter plates were coated with protective antigen (gift from Joe Farchaus, Bacteriology Division) (1 ug/ml) in PBS and allowed to absorb overnight at 4° C. Four fold serum dilutions in blocking buffer were applied to the plates and incubated at 37° C. for 1 hour. After washing, an anti-mouse secondary antibody (HRP conjugated) was added to the plate and incubated for an additional hour at 37° C. After washing, bound antibody was detected colormetrically using ABTS as a substrate.

Challenge of mice.

Anthrax challenge: C57BL/6 or A/J mice were challenged subcutaneously with 12-32. LD₅₀ B. anthracis (Sterne) 31 days after the last inoculation.

EXAMPLE 1 Packaging and Expression of PA-replicon

The PA-replicon was efficiently packaged into VRPs using the double helper system. Stock solutions contained about 105 infectious units of purified PA-VRP per milliliter. No replication competent VEE virus was detected in any of the preparations. A western blot of cell lysates, generated from BHK cells infected with PA-VRP, demonstrates a product of approximately 85 kDa (FIG. 2). Because the PA-VRP expression product contains a 29 amino acid prokaryotic secretory signal, which is cleaved from the standard, the PA product from the BHK cells appears larger than the PA standard.

EXAMPLE 2 Protection Against Challenge With B. anthracis

The results of the animal studies demonstrated that PA from B. anthracis could be used to immunize and protect mice from a lethal challenge of B. anthracis (Sterne strain). Although the Sterne strain is attenuated in some animals, it is virulent in mice. Controls in the experiment included mice vaccinated with the current human vaccine (anthrax vaccine absorbed, AVA) which protected all mice, and mice immunized with the Lassa N-replicon which expressed an antigen irrelevant to anthrax protection which failed to protect the mice. FIG. 3A shows ELISA titers and survival for C57Bl/6 mice inoculated with two to four doses of PA-VRP. Seventy percent of the C57Bl/6 mice which received three inoculations of the PA-VRP were protected whereas 90% of the C57Bl/6 mice which received four inoculations were protected from an otherwise lethal challenge of B. anthracis (Sterne strain). The geometric mean of the serum ELISA titers to PA of C57Bl/6 mice given four doses of the PA-replicon was 150500, as compared to 264 for mice that were inoculated with the negative control replicon. FIG. 3B shows ELISA titers and survival for A/J mice inoculated with two to four doses of PA-VRP. Three inoculations of the PA-VRP protected 70% of the A/J mice, whereas four inoculations protected 90% of the A/J mice from an otherwise lethal challenge of the B. anthracis (Sterne strain). The geometric mean of the serum ELISA titers against PA in A/J mice given four doses of the PA-replicon was 223336, as compared to 100 for mice which were inoculated with the negative control replicon. As expected, none of the mice (from either strain) which were inoculated with the negative control replicon survived challenge with B. anthracis (Sterne strain).

Discussion/Conclusion

Since VEE virus replicates in the cytoplasm of eukaryotic cells, the VEE replicon vaccine vector is a useful tool for the expression of prokaryotic genes in eukaryotic cells. Cytoplasmic expression of genes alleviates the difficulties imposed by splicing and nuclear transport of mRNA. We used the VEE replicon as a way to express the prokaryotic PA gene in eukaryotic cells and to develop a new vaccine candidate against anthrax.

The human AVA contains mostly PA protein and is presumed to protect humans by eliciting an antibody response that can neutralize the PA portion of anthrax toxin produced by invading B. anthracis. After neutralization of the toxin, the immune system destroys the invading bacteria. In order to model the human disease, we chose to use mice and the Sterne strain of B. anthracis. The Sterne strain produces anthrax toxin (encoded on the pXO1 plasmid) but lacks a capsule (encoded on the pXO2 plasmid). Mice exposed to large quantities of Sterne (ranging from 10³ to 10⁸ spores for the different mouse strains) are not able to overcome the effects of the toxin produced by the bacteria so they succumb to infection. We hypothesized that by immunizing the mice with PA, thereby inducing neutralizing antibodies to the PA portion of the toxin produced by a challenge inoculum, that them ice would be protected.

A VEE replicon was constructed which expressed the PA gene from B. anthracis and was evaluated for in vitro expression, in vivo immunogenicity, and protective efficacy. C57Bl/6 and A/J mice demonstrated increasing antibody responses to PA when inoculated with increasing doses of PA-VRP. The two mouse strains inoculated with up to four doses of PA-VRP displayed increased protection against a lethal challenge with B. anthracis (Sterne strain). The use of mice and the Sterne strain of B. anthracis useful as a model system for studying the immunogenicity and efficacy of replicon based anthrax vaccines.

8 1 2295 DNA Bacillus anthracis 1 atgaaaaaac gaaaagtgtt aataccatta atggcattgt ctacgatatt agtttcaagc 60 acaggtaatt tagaggtgat tcaggcagaa gttaaacagg agaaccggtt attaaatgaa 120 tcagaatcaa gttcccaggg gttactagga tactatttta gtgatttgaa ttttcaagca 180 cccatggtgg ttacctcttc tactacaggg gatttatcta ttcctagttc tgagttagaa 240 aatattccat cggaaaacca atattttcaa tctgctattt ggtcaggatt tatcaaagtt 300 aagaagagtg atgaatatac atttgctact tccgctgata atcatgtaac aatgtgggta 360 gatgaccaag aagtgattaa taaagcttct aattctaaca aaatcagatt agaaaaagga 420 agattatatc aaataaaaat tcaatatcaa cgagaaaatc ctactgaaaa aggattggat 480 ttcaagttgt actggaccga ttctcaaaat aaaaaagaag tgatttctag tgataactta 540 caattgccag aattaaaaca aaaatcttcg aactcaagaa aaaagacaag tacaagtgct 600 ggacctacgg ttccagaccg tgacaatgat ggaatccctg attcattaga ggtagaagga 660 tatacggttg atgtcaaaaa taaaagaact tttctttcac catggatttc taatattcat 720 gaaaagaaag gattaaccaa atataaatca tctcctgaaa aatggagcac ggcttctgat 780 ccgtacagtg atttcgaaaa ggttacagga cggattgata agaatgtatc accagaggca 840 agacaccccc ttgtggcagc ttatccgatt gtacatgtag atatggagaa tattattctc 900 tcaaaaaatg aggatcaatc cacacagaat actgatagtg aaacgagaac aataagtaaa 960 aatacttcta caagtaggac acatactagt gaagtacatg gaaatgcaga agtgcatgcg 1020 tcgttctttg atattggtgg gagtgtatct gcaggattta gtaattcgaa ttcaagtacg 1080 gtcgcaattg atcattcact atctctagca ggggaaagaa cttgggctga aacaatgggt 1140 ttaaataccg ctgatacagc aagattaaat gccaatatta gatatgtaaa tactgggacg 1200 gctccaatct acaacgtgtt accaacgact tcgttagtgt taggaaaaaa tcaaacactc 1260 gcgacaatta aagctaagga aaaccaatta agtcaaatac ttgcacctaa taattattat 1320 ccttctaaaa acttggcgcc aatcgcatta aatgcacaag acgatttcag ttctactcca 1380 attacaatga attacaatca atttcttgag ttagaaaaaa cgaaacaatt aagattagat 1440 acggatcaag tatatgggaa tatagcaaca tacaattttg aaaatggaag agtgagggtg 1500 gatacaggct cgaactggag tgaagtgtta ccgcaaattc aagaaacaac tgcacgtatc 1560 atttttaatg gaaaagattt aaatctggta gaaaggcgga tagcggcggt taatcctagt 1620 gatccattag aaacgactaa accggatatg acattaaaag aagcccttaa aatagcattt 1680 ggatttaacg aaccgaatgg aaacttacaa tatcaaggga aagacataac cgaatttgat 1740 tttaatttcg atcaacaaac atctcaaaat atcaagaatc agttagcgga attaaacgca 1800 actaacatat atactgtatt agataaaatc aaattaaatg caaaaatgaa tattttaata 1860 agagataaac gttttcatta tgatagaaat aacatagcag ttggggcgga tgagtcagta 1920 gttaaggagg ctcatagaga agtaattaat tcgtcaacag agggattatt gttaaatatt 1980 gataaggata taagaaaaat attatcaggt tatattgtag aaattgaaga tactgaaggg 2040 cttaaagaag ttataaatga cagatatgat atgttgaata tttctagttt acggcaagat 2100 ggaaaaacat ttatagattt taaaaaatat aatgataaat taccgttata tataagtaat 2160 cccaattata aggtaaatgt atatgctgtt actaaagaaa acactattat taatcctagt 2220 gagaatgggg atactagtac caacgggatc aagaaaattt taatcttttc taaaaaaggc 2280 tatgagatag gataa 2295 2 2211 DNA Bacillus anthracis 2 atggaagtta aacaggagaa ccggttatta aatgaatcag aatcaagttc ccaggggtta 60 ctaggatact attttagtga tttgaatttt caagcaccca tggtggttac ctcttctact 120 acaggggatt tatctattcc tagttctgag ttagaaaata ttccatcgga aaaccaatat 180 tttcaatctg ctatttggtc aggatttatc aaagttaaga agagtgatga atatacattt 240 gctacttccg ctgataatca tgtaacaatg tgggtagatg accaagaagt gattaataaa 300 gcttctaatt ctaacaaaat cagattagaa aaaggaagat tatatcaaat aaaaattcaa 360 tatcaacgag aaaatcctac tgaaaaagga ttggatttca agttgtactg gaccgattct 420 caaaataaaa aagaagtgat ttctagtgat aacttacaat tgccagaatt aaaacaaaaa 480 tcttcgaact caagaaaaaa gcgaagtaca agtgctggac ctacggttcc agaccgtgac 540 aatgatggaa tccctgattc attagaggta gaaggatata cggttgatgt caaaaataaa 600 agaacttttc tttcaccatg gatttctaat attcatgaaa agaaaggatt aaccaaatat 660 aaatcatctc ctgaaaaatg gagcacggct tctgatccgt acagtgattt cgaaaaggtt 720 acaggacgga ttgataagaa tgtatcacca gaggcaagac acccccttgt ggcagcttat 780 ccgattgtac atgtagatat ggagaatatt attctctcaa aaaatgagga tcaatccaca 840 cagaatactg atagtgaaac gagaacaata agtaaaaata cttctacaag taggacacat 900 actagtgaag tacatggaaa tgcagaagtg catgcgtcgt tctttgatat tggtgggagt 960 gtatctgcag gatttagtaa ttcgaattca agtacggtcg caattgatca ttcactatct 1020 ctagcagggg aaagaacttg ggctgaaaca atgggtttaa ataccgctga tacagcaaga 1080 ttaaatgcca atattagata tgtaaatact gggacggctc caatctacaa cgtgttacca 1140 acgacttcgt tagtgttagg aaaaaatcaa acactcgcga caattaaagc taaggaaaac 1200 caattaagtc aaatacttgc acctaataat tattatcctt ctaaaaactt ggcgccaatc 1260 gcattaaatg cacaagacga tttcagttct actccaatta caatgaatta caatcaattt 1320 cttgagttag aaaaaacgaa acaattaaga ttagatacgg atcaagtata tgggaatata 1380 gcaacataca attttgaaaa tggaagagtg agggtggata caggctcgaa ctggagtgaa 1440 gtgttaccgc aaattcaaga aacaactgca cgtatcattt ttaatggaaa agatttaaat 1500 ctggtagaaa ggcggatagc ggcggttaat cctagtgatc cattagaaac gactaaaccg 1560 gatatgacat taaaagaagc ccttaaaata gcatttggat ttaacgaacc gaatggaaac 1620 ttacaatatc aagggaaaga cataaccgaa tttgatttta atttcgatca acaaacatct 1680 caaaatatca agaatcagtt agcggaatta aacgcaacta acatatatac tgtattagat 1740 aaaatcaaat taaatgcaaa aatgaatatt ttaataagag ataaacgttt tcattatgat 1800 agaaataaca tagcagttgg ggcggatgag tcagtagtta aggaggctca tagagaagta 1860 attaattcgt caacagaggg attattgtta aatattgata aggatataag aaaaatatta 1920 tcaggttata ttgtagaaat tgaagatact gaagggctta aagaagttat aaatgacaga 1980 tatgatatgt tgaatatttc tagtttacgg caagatggaa aaacatttat agattttaaa 2040 aaatataatg ataaattacc gttatatata agtaatccca attataaggt aaatgtatat 2100 gctgttacta aagaaaacac tattattaat cctagtgaga atggggatac tagtaccaac 2160 gggatcaaga aaattttaat cttttctaaa aaaggctatg agataggata a 2211 3 2292 DNA Bacillus anthracis 3 atggatgcaa tgaagagagg gctctgctgt gtgctgctgc tgtgtggagc agtcttcgtt 60 tcggctagcg aggtgattca ggcagaagtt aaacaggaga accggttatt aaatgaatca 120 gaatcaagtt cccaggggtt actaggatac tattttagtg atttgaattt tcaagcaccc 180 atggtggtta cctcttctac tacaggggat ttatctattc ctagttctga gttagaaaat 240 attccatcgg aaaaccaata ttttcaatct gctatttggt caggatttat caaagttaag 300 aagagtgatg aatatacatt tgctacttcc gctgataatc atgtaacaat gtgggtagat 360 gaccaagaag tgattaataa agcttctaat tctaacaaaa tcagattaga aaaaggaaga 420 ttatatcaaa taaaaattca atatcaacga gaaaatccta ctgaaaaagg attggatttc 480 aagttgtact ggaccgattc tcaaaataaa aaagaagtga tttctagtga taacttacaa 540 ttgccagaat taaaacaaaa atcttcgaac tcaagaaaaa agcgaagtac aagtgctgga 600 cctacggttc cagaccgtga caatgatgga atccctgatt cattagaggt agaaggatat 660 acggttgatg tcaaaaataa aagaactttt ctttcaccat ggatttctaa tattcatgaa 720 aagaaaggat taaccaaata taaatcatct cctgaaaaat ggagcacggc ttctgatccg 780 tacagtgatt tcgaaaaggt tacaggacgg attgataaga atgtatcacc agaggcaaga 840 cacccccttg tggcagctta tccgattgta catgtagata tggagaatat tattctctca 900 aaaaatgagg atcaatccac acagaatact gatagtgaaa cgagaacaat aagtaaaaat 960 acttctacaa gtaggacaca tactagtgaa gtacatggaa atgcagaagt gcatgcgtcg 1020 ttctttgata ttggtgggag tgtatctgca ggatttagta attcgaattc aagtacggtc 1080 gcaattgatc attcactatc tctagcaggg gaaagaactt gggctgaaac aatgggttta 1140 aataccgctg atacagcaag attaaatgcc aatattagat atgtaaatac tgggacggct 1200 ccaatctaca acgtgttacc aacgacttcg ttagtgttag gaaaaaatca aacactcgcg 1260 acaattaaag ctaaggaaaa ccaattaagt caaatacttg cacctaataa ttattatcct 1320 tctaaaaact tggcgccaat cgcattaaat gcacaagacg atttcagttc tactccaatt 1380 acaatgaatt acaatcaatt tcttgagtta gaaaaaacga aacaattaag attagatacg 1440 gatcaagtat atgggaatat agcaacatac aattttgaaa atggaagagt gagggtggat 1500 acaggctcga actggagtga agtgttaccg caaattcaag aaacaactgc acgtatcatt 1560 tttaatggaa aagatttaaa tctggtagaa aggcggatag cggcggttaa tcctagtgat 1620 ccattagaaa cgactaaacc ggatatgaca ttaaaagaag cccttaaaat agcatttgga 1680 tttaacgaac cgaatggaaa cttacaatat caagggaaag acataaccga atttgatttt 1740 aatttcgatc aacaaacatc tcaaaatatc aagaatcagt tagcggaatt aaacgcaact 1800 aacatatata ctgtattaga taaaatcaaa ttaaatgcaa aaatgaatat tttaataaga 1860 gataaacgtt ttcattatga tagaaataac atagcagttg gggcggatga gtcagtagtt 1920 aaggaggctc atagagaagt aattaattcg tcaacagagg gattattgtt aaatattgat 1980 aaggatataa gaaaaatatt atcaggttat attgtagaaa ttgaagatac tgaagggctt 2040 aaagaagtta taaatgacag atatgatatg ttgaatattt ctagtttacg gcaagatgga 2100 aaaacattta tagattttaa aaaatataat gataaattac cgttatatat aagtaatccc 2160 aattataagg taaatgtata tgctgttact aaagaaaaca ctattattaa tcctagtgag 2220 aatggggata ctagtaccaa cgggatcaag aaaattttaa tcttttctaa aaaaggctat 2280 gagataggat aa 2292 4 1710 DNA Bacillus anthracis 4 atgagtacaa gtgctggacc tacggttcca gaccgtgaca atgatggaat ccctgattca 60 ttagaggtag aaggatatac ggttgatgtc aaaaataaaa gaacttttct ttcaccatgg 120 atttctaata ttcatgaaaa gaaaggatta accaaatata aatcatctcc tgaaaaatgg 180 agcacggctt ctgatccgta cagtgatttc gaaaaggtta caggacggat tgataagaat 240 gtatcaccag aggcaagaca cccccttgtg gcagcttatc cgattgtaca tgtagatatg 300 gagaatatta ttctctcaaa aaatgaggat caatccacac agaatactga tagtgaaacg 360 agaacaataa gtaaaaatac ttctacaagt aggacacata ctagtgaagt acatggaaat 420 gcagaagtgc atgcgtcgtt ctttgatatt ggtgggagtg tatctgcagg atttagtaat 480 tcgaattcaa gtacggtcgc aattgatcat tcactatctc tagcagggga aagaacttgg 540 gctgaaacaa tgggtttaaa taccgctgat acagcaagat taaatgccaa tattagatat 600 gtaaatactg ggacggctcc aatctacaac gtgttaccaa cgacttcgtt agtgttagga 660 aaaaatcaaa cactcgcgac aattaaagct aaggaaaacc aattaagtca aatacttgca 720 cctaataatt attatccttc taaaaacttg gcgccaatcg cattaaatgc acaagacgat 780 ttcagttcta ctccaattac aatgaattac aatcaatttc ttgagttaga aaaaacgaaa 840 caattaagat tagatacgga tcaagtatat gggaatatag caacatacaa ttttgaaaat 900 ggaagagtga gggtggatac aggctcgaac tggagtgaag tgttaccgca aattcaagaa 960 acaactgcac gtatcatttt taatggaaaa gatttaaatc tggtagaaag gcggatagcg 1020 gcggttaatc ctagtgatcc attagaaacg actaaaccgg atatgacatt aaaagaagcc 1080 cttaaaatag catttggatt taacgaaccg aatggaaact tacaatatca agggaaagac 1140 ataaccgaat ttgattttaa tttcgatcaa caaacatctc aaaatatcaa gaatcagtta 1200 gcggaattaa acgcaactaa catatatact gtattagata aaatcaaatt aaatgcaaaa 1260 atgaatattt taataagaga taaacgtttt cattatgata gaaataacat agcagttggg 1320 gcggatgagt cagtagttaa ggaggctcat agagaagtaa ttaattcgtc aacagaggga 1380 ttattgttaa atattgataa ggatataaga aaaatattat caggttatat tgtagaaatt 1440 gaagatactg aagggcttaa agaagttata aatgacagat atgatatgtt gaatatttct 1500 agtttacggc aagatggaaa aacatttata gattttaaaa aatataatga taaattaccg 1560 ttatatataa gtaatcccaa ttataaggta aatgtatatg ctgttactaa agaaaacact 1620 attattaatc ctagtgagaa tggggatact agtaccaacg ggatcaagaa aattttaatc 1680 ttttctaaaa aaggctatga gataggataa 1710 5 763 PRT Bacillus anthracis 5 Met Asp Ala Met Lys Arg Gly Leu Cys Cys Val Leu Leu Leu Cys Gly 1 5 10 15 Ala Val Phe Val Ser Ala Ser Glu Val Ile Gln Ala Glu Val Lys Gln 20 25 30 Glu Asn Arg Leu Leu Asn Glu Ser Glu Ser Ser Ser Gln Gly Leu Leu 35 40 45 Gly Tyr Tyr Phe Ser Asp Leu Asn Phe Gln Ala Pro Met Val Val Thr 50 55 60 Ser Ser Thr Thr Gly Asp Leu Ser Ile Pro Ser Ser Glu Leu Glu Asn 65 70 75 80 Ile Pro Ser Glu Asn Gln Tyr Phe Gln Ser Ala Ile Trp Ser Gly Phe 85 90 95 Ile Lys Val Lys Lys Ser Asp Glu Tyr Thr Phe Ala Thr Ser Ala Asp 100 105 110 Asn His Val Thr Met Trp Val Asp Asp Gln Glu Val Ile Asn Lys Ala 115 120 125 Ser Asn Ser Asn Lys Ile Arg Leu Glu Lys Gly Arg Leu Tyr Gln Ile 130 135 140 Lys Ile Gln Tyr Gln Arg Glu Asn Pro Thr Glu Lys Gly Leu Asp Phe 145 150 155 160 Lys Leu Tyr Trp Thr Asp Ser Gln Asn Lys Lys Glu Val Ile Ser Ser 165 170 175 Asp Asn Leu Gln Leu Pro Glu Leu Lys Gln Lys Ser Ser Asn Ser Arg 180 185 190 Lys Lys Arg Ser Thr Ser Ala Gly Pro Thr Val Pro Asp Arg Asp Asn 195 200 205 Asp Gly Ile Pro Asp Ser Leu Glu Val Glu Gly Tyr Thr Val Asp Val 210 215 220 Lys Asn Lys Arg Thr Phe Leu Ser Pro Trp Ile Ser Asn Ile His Glu 225 230 235 240 Lys Lys Gly Leu Thr Lys Tyr Lys Ser Ser Pro Glu Lys Trp Ser Thr 245 250 255 Ala Ser Asp Pro Tyr Ser Asp Phe Glu Lys Val Thr Gly Arg Ile Asp 260 265 270 Lys Asn Val Ser Pro Glu Ala Arg His Pro Leu Val Ala Ala Tyr Pro 275 280 285 Ile Val His Val Asp Met Glu Asn Ile Ile Leu Ser Lys Asn Glu Asp 290 295 300 Gln Ser Thr Gln Asn Thr Asp Ser Glu Thr Arg Thr Ile Ser Lys Asn 305 310 315 320 Thr Ser Thr Ser Arg Thr His Thr Ser Glu Val His Gly Asn Ala Glu 325 330 335 Val His Ala Ser Phe Phe Asp Ile Gly Gly Ser Val Ser Ala Gly Phe 340 345 350 Ser Asn Ser Asn Ser Ser Thr Val Ala Ile Asp His Ser Leu Ser Leu 355 360 365 Ala Gly Glu Arg Thr Trp Ala Glu Thr Met Gly Leu Asn Thr Ala Asp 370 375 380 Thr Ala Arg Leu Asn Ala Asn Ile Arg Tyr Val Asn Thr Gly Thr Ala 385 390 395 400 Pro Ile Tyr Asn Val Leu Pro Thr Thr Ser Leu Val Leu Gly Lys Asn 405 410 415 Gln Thr Leu Ala Thr Ile Lys Ala Lys Glu Asn Gln Leu Ser Gln Ile 420 425 430 Leu Ala Pro Asn Asn Tyr Tyr Pro Ser Lys Asn Leu Ala Pro Ile Ala 435 440 445 Leu Asn Ala Gln Asp Asp Phe Ser Ser Thr Pro Ile Thr Met Asn Tyr 450 455 460 Asn Gln Phe Leu Glu Leu Glu Lys Thr Lys Gln Leu Arg Leu Asp Thr 465 470 475 480 Asp Gln Val Tyr Gly Asn Ile Ala Thr Tyr Asn Phe Glu Asn Gly Arg 485 490 495 Val Arg Val Asp Thr Gly Ser Asn Trp Ser Glu Val Leu Pro Gln Ile 500 505 510 Gln Glu Thr Thr Ala Arg Ile Ile Phe Asn Gly Lys Asp Leu Asn Leu 515 520 525 Val Glu Arg Arg Ile Ala Ala Val Asn Pro Ser Asp Pro Leu Glu Thr 530 535 540 Thr Lys Pro Asp Met Thr Leu Lys Glu Ala Leu Lys Ile Ala Phe Gly 545 550 555 560 Phe Asn Glu Pro Asn Gly Asn Leu Gln Tyr Gln Gly Lys Asp Ile Thr 565 570 575 Glu Phe Asp Phe Asn Phe Asp Gln Gln Thr Ser Gln Asn Ile Lys Asn 580 585 590 Gln Leu Ala Glu Leu Asn Ala Thr Asn Ile Tyr Thr Val Leu Asp Lys 595 600 605 Ile Lys Leu Asn Ala Lys Met Asn Ile Leu Ile Arg Asp Lys Arg Phe 610 615 620 His Tyr Asp Arg Asn Asn Ile Ala Val Gly Ala Asp Glu Ser Val Val 625 630 635 640 Lys Glu Ala His Arg Glu Val Ile Asn Ser Ser Thr Glu Gly Leu Leu 645 650 655 Leu Asn Ile Asp Lys Asp Ile Arg Lys Ile Leu Ser Gly Tyr Ile Val 660 665 670 Glu Ile Glu Asp Thr Glu Gly Leu Lys Glu Val Ile Asn Asp Arg Tyr 675 680 685 Asp Met Leu Asn Ile Ser Ser Leu Arg Gln Asp Gly Lys Thr Phe Ile 690 695 700 Asp Phe Lys Lys Tyr Asn Asp Lys Leu Pro Leu Tyr Ile Ser Asn Pro 705 710 715 720 Asn Tyr Lys Val Asn Val Tyr Ala Val Thr Lys Glu Asn Thr Ile Ile 725 730 735 Asn Pro Ser Glu Asn Gly Asp Thr Ser Thr Asn Gly Ile Lys Lys Ile 740 745 750 Leu Ile Phe Ser Lys Lys Gly Tyr Glu Ile Gly 755 760 6 764 PRT Bacillus anthracis 6 Met Lys Lys Arg Lys Val Leu Ile Pro Leu Met Ala Leu Ser Thr Ile 1 5 10 15 Leu Val Ser Ser Thr Gly Asn Leu Glu Val Ile Gln Ala Glu Val Lys 20 25 30 Gln Glu Asn Arg Leu Leu Asn Glu Ser Glu Ser Ser Ser Gln Gly Leu 35 40 45 Leu Gly Tyr Tyr Phe Ser Asp Leu Asn Phe Gln Ala Pro Met Val Val 50 55 60 Thr Ser Ser Thr Thr Gly Asp Leu Ser Ile Pro Ser Ser Glu Leu Glu 65 70 75 80 Asn Ile Pro Ser Glu Asn Gln Tyr Phe Gln Ser Ala Ile Trp Ser Gly 85 90 95 Phe Ile Lys Val Lys Lys Ser Asp Glu Tyr Thr Phe Ala Thr Ser Ala 100 105 110 Asp Asn His Val Thr Met Trp Val Asp Asp Gln Glu Val Ile Asn Lys 115 120 125 Ala Ser Asn Ser Asn Lys Ile Arg Leu Glu Lys Gly Arg Leu Tyr Gln 130 135 140 Ile Lys Ile Gln Tyr Gln Arg Glu Asn Pro Thr Glu Lys Gly Leu Asp 145 150 155 160 Phe Lys Leu Tyr Trp Thr Asp Ser Gln Asn Lys Lys Glu Val Ile Ser 165 170 175 Ser Asp Asn Leu Gln Leu Pro Glu Leu Lys Gln Lys Ser Ser Asn Ser 180 185 190 Arg Lys Lys Arg Ser Thr Ser Ala Gly Pro Thr Val Pro Asp Arg Asp 195 200 205 Asn Asp Gly Ile Pro Asp Ser Leu Glu Val Glu Gly Tyr Thr Val Asp 210 215 220 Val Lys Asn Lys Arg Thr Phe Leu Ser Pro Trp Ile Ser Asn Ile His 225 230 235 240 Glu Lys Lys Gly Leu Thr Lys Tyr Lys Ser Ser Pro Glu Lys Trp Ser 245 250 255 Thr Ala Ser Asp Pro Tyr Ser Asp Phe Glu Lys Val Thr Gly Arg Ile 260 265 270 Asp Lys Asn Val Ser Pro Glu Ala Arg His Pro Leu Val Ala Ala Tyr 275 280 285 Pro Ile Val His Val Asp Met Glu Asn Ile Ile Leu Ser Lys Asn Glu 290 295 300 Asp Gln Ser Thr Gln Asn Thr Asp Ser Glu Thr Arg Thr Ile Ser Lys 305 310 315 320 Asn Thr Ser Thr Ser Arg Thr His Thr Ser Glu Val His Gly Asn Ala 325 330 335 Glu Val His Ala Ser Phe Phe Asp Ile Gly Gly Ser Val Ser Ala Gly 340 345 350 Phe Ser Asn Ser Asn Ser Ser Thr Val Ala Ile Asp His Ser Leu Ser 355 360 365 Leu Ala Gly Glu Arg Thr Trp Ala Glu Thr Met Gly Leu Asn Thr Ala 370 375 380 Asp Thr Ala Arg Leu Asn Ala Asn Ile Arg Tyr Val Asn Thr Gly Thr 385 390 395 400 Ala Pro Ile Tyr Asn Val Leu Pro Thr Thr Ser Leu Val Leu Gly Lys 405 410 415 Asn Gln Thr Leu Ala Thr Ile Lys Ala Lys Glu Asn Gln Leu Ser Gln 420 425 430 Ile Leu Ala Pro Asn Asn Tyr Tyr Pro Ser Lys Asn Leu Ala Pro Ile 435 440 445 Ala Leu Asn Ala Gln Asp Asp Phe Ser Ser Thr Pro Ile Thr Met Asn 450 455 460 Tyr Asn Gln Phe Leu Glu Leu Glu Lys Thr Lys Gln Leu Arg Leu Asp 465 470 475 480 Thr Asp Gln Val Tyr Gly Asn Ile Ala Thr Tyr Asn Phe Glu Asn Gly 485 490 495 Arg Val Arg Val Asp Thr Gly Ser Asn Trp Ser Glu Val Leu Pro Gln 500 505 510 Ile Gln Glu Thr Thr Ala Arg Ile Ile Phe Asn Gly Lys Asp Leu Asn 515 520 525 Leu Val Glu Arg Arg Ile Ala Ala Val Asn Pro Ser Asp Pro Leu Glu 530 535 540 Thr Thr Lys Pro Asp Met Thr Leu Lys Glu Ala Leu Lys Ile Ala Phe 545 550 555 560 Gly Phe Asn Glu Pro Asn Gly Asn Leu Gln Tyr Gln Gly Lys Asp Ile 565 570 575 Thr Glu Phe Asp Phe Asn Phe Asp Gln Gln Thr Ser Gln Asn Ile Lys 580 585 590 Asn Gln Leu Ala Glu Leu Asn Ala Thr Asn Ile Tyr Thr Val Leu Asp 595 600 605 Lys Ile Lys Leu Asn Ala Lys Met Asn Ile Leu Ile Arg Asp Lys Arg 610 615 620 Phe His Tyr Asp Arg Asn Asn Ile Ala Val Gly Ala Asp Glu Ser Val 625 630 635 640 Val Lys Glu Ala His Arg Glu Val Ile Asn Ser Ser Thr Glu Gly Leu 645 650 655 Leu Leu Asn Ile Asp Lys Asp Ile Arg Lys Ile Leu Ser Gly Tyr Ile 660 665 670 Val Glu Ile Glu Asp Thr Glu Gly Leu Lys Glu Val Ile Asn Asp Arg 675 680 685 Tyr Asp Met Leu Asn Ile Ser Ser Leu Arg Gln Asp Gly Lys Thr Phe 690 695 700 Ile Asp Phe Lys Lys Tyr Asn Asp Lys Leu Pro Leu Tyr Ile Ser Asn 705 710 715 720 Pro Asn Tyr Lys Val Asn Val Tyr Ala Val Thr Lys Glu Asn Thr Ile 725 730 735 Ile Asn Pro Ser Glu Asn Gly Asp Thr Ser Thr Asn Gly Ile Lys Lys 740 745 750 Ile Leu Ile Phe Ser Lys Lys Gly Tyr Glu Ile Gly 755 760 7 736 PRT Bacillus anthracis 7 Met Glu Val Lys Gln Glu Asn Arg Leu Leu Asn Glu Ser Glu Ser Ser 1 5 10 15 Ser Gln Gly Leu Leu Gly Tyr Tyr Phe Ser Asp Leu Asn Phe Gln Ala 20 25 30 Pro Met Val Val Thr Ser Ser Thr Thr Gly Asp Leu Ser Ile Pro Ser 35 40 45 Ser Glu Leu Glu Asn Ile Pro Ser Glu Asn Gln Tyr Phe Gln Ser Ala 50 55 60 Ile Trp Ser Gly Phe Ile Lys Val Lys Lys Ser Asp Glu Tyr Thr Phe 65 70 75 80 Ala Thr Ser Ala Asp Asn His Val Thr Met Trp Val Asp Asp Gln Glu 85 90 95 Val Ile Asn Lys Ala Ser Asn Ser Asn Lys Ile Arg Leu Glu Lys Gly 100 105 110 Arg Leu Tyr Gln Ile Lys Ile Gln Tyr Gln Arg Glu Asn Pro Thr Glu 115 120 125 Lys Gly Leu Asp Phe Lys Leu Tyr Trp Thr Asp Ser Gln Asn Lys Lys 130 135 140 Glu Val Ile Ser Ser Asp Asn Leu Gln Leu Pro Glu Leu Lys Gln Lys 145 150 155 160 Ser Ser Asn Ser Arg Lys Lys Arg Ser Thr Ser Ala Gly Pro Thr Val 165 170 175 Pro Asp Arg Asp Asn Asp Gly Ile Pro Asp Ser Leu Glu Val Glu Gly 180 185 190 Tyr Thr Val Asp Val Lys Asn Lys Arg Thr Phe Leu Ser Pro Trp Ile 195 200 205 Ser Asn Ile His Glu Lys Lys Gly Leu Thr Lys Tyr Lys Ser Ser Pro 210 215 220 Glu Lys Trp Ser Thr Ala Ser Asp Pro Tyr Ser Asp Phe Glu Lys Val 225 230 235 240 Thr Gly Arg Ile Asp Lys Asn Val Ser Pro Glu Ala Arg His Pro Leu 245 250 255 Val Ala Ala Tyr Pro Ile Val His Val Asp Met Glu Asn Ile Ile Leu 260 265 270 Ser Lys Asn Glu Asp Gln Ser Thr Gln Asn Thr Asp Ser Glu Thr Arg 275 280 285 Thr Ile Ser Lys Asn Thr Ser Thr Ser Arg Thr His Thr Ser Glu Val 290 295 300 His Gly Asn Ala Glu Val His Ala Ser Phe Phe Asp Ile Gly Gly Ser 305 310 315 320 Val Ser Ala Gly Phe Ser Asn Ser Asn Ser Ser Thr Val Ala Ile Asp 325 330 335 His Ser Leu Ser Leu Ala Gly Glu Arg Thr Trp Ala Glu Thr Met Gly 340 345 350 Leu Asn Thr Ala Asp Thr Ala Arg Leu Asn Ala Asn Ile Arg Tyr Val 355 360 365 Asn Thr Gly Thr Ala Pro Ile Tyr Asn Val Leu Pro Thr Thr Ser Leu 370 375 380 Val Leu Gly Lys Asn Gln Thr Leu Ala Thr Ile Lys Ala Lys Glu Asn 385 390 395 400 Gln Leu Ser Gln Ile Leu Ala Pro Asn Asn Tyr Tyr Pro Ser Lys Asn 405 410 415 Leu Ala Pro Ile Ala Leu Asn Ala Gln Asp Asp Phe Ser Ser Thr Pro 420 425 430 Ile Thr Met Asn Tyr Asn Gln Phe Leu Glu Leu Glu Lys Thr Lys Gln 435 440 445 Leu Arg Leu Asp Thr Asp Gln Val Tyr Gly Asn Ile Ala Thr Tyr Asn 450 455 460 Phe Glu Asn Gly Arg Val Arg Val Asp Thr Gly Ser Asn Trp Ser Glu 465 470 475 480 Val Leu Pro Gln Ile Gln Glu Thr Thr Ala Arg Ile Ile Phe Asn Gly 485 490 495 Lys Asp Leu Asn Leu Val Glu Arg Arg Ile Ala Ala Val Asn Pro Ser 500 505 510 Asp Pro Leu Glu Thr Thr Lys Pro Asp Met Thr Leu Lys Glu Ala Leu 515 520 525 Lys Ile Ala Phe Gly Phe Asn Glu Pro Asn Gly Asn Leu Gln Tyr Gln 530 535 540 Gly Lys Asp Ile Thr Glu Phe Asp Phe Asn Phe Asp Gln Gln Thr Ser 545 550 555 560 Gln Asn Ile Lys Asn Gln Leu Ala Glu Leu Asn Ala Thr Asn Ile Tyr 565 570 575 Thr Val Leu Asp Lys Ile Lys Leu Asn Ala Lys Met Asn Ile Leu Ile 580 585 590 Arg Asp Lys Arg Phe His Tyr Asp Arg Asn Asn Ile Ala Val Gly Ala 595 600 605 Asp Glu Ser Val Val Lys Glu Ala His Arg Glu Val Ile Asn Ser Ser 610 615 620 Thr Glu Gly Leu Leu Leu Asn Ile Asp Lys Asp Ile Arg Lys Ile Leu 625 630 635 640 Ser Gly Tyr Ile Val Glu Ile Glu Asp Thr Glu Gly Leu Lys Glu Val 645 650 655 Ile Asn Asp Arg Tyr Asp Met Leu Asn Ile Ser Ser Leu Arg Gln Asp 660 665 670 Gly Lys Thr Phe Ile Asp Phe Lys Lys Tyr Asn Asp Lys Leu Pro Leu 675 680 685 Tyr Ile Ser Asn Pro Asn Tyr Lys Val Asn Val Tyr Ala Val Thr Lys 690 695 700 Glu Asn Thr Ile Ile Asn Pro Ser Glu Asn Gly Asp Thr Ser Thr Asn 705 710 715 720 Gly Ile Lys Lys Ile Leu Ile Phe Ser Lys Lys Gly Tyr Glu Ile Gly 725 730 735 8 569 PRT Bacillus anthracis 8 Met Ser Thr Ser Ala Gly Pro Thr Val Pro Asp Arg Asp Asn Asp Gly 1 5 10 15 Ile Pro Asp Ser Leu Glu Val Glu Gly Tyr Thr Val Asp Val Lys Asn 20 25 30 Lys Arg Thr Phe Leu Ser Pro Trp Ile Ser Asn Ile His Glu Lys Lys 35 40 45 Gly Leu Thr Lys Tyr Lys Ser Ser Pro Glu Lys Trp Ser Thr Ala Ser 50 55 60 Asp Pro Tyr Ser Asp Phe Glu Lys Val Thr Gly Arg Ile Asp Lys Asn 65 70 75 80 Val Ser Pro Glu Ala Arg His Pro Leu Val Ala Ala Tyr Pro Ile Val 85 90 95 His Val Asp Met Glu Asn Ile Ile Leu Ser Lys Asn Glu Asp Gln Ser 100 105 110 Thr Gln Asn Thr Asp Ser Glu Thr Arg Thr Ile Ser Lys Asn Thr Ser 115 120 125 Thr Ser Arg Thr His Thr Ser Glu Val His Gly Asn Ala Glu Val His 130 135 140 Ala Ser Phe Phe Asp Ile Gly Gly Ser Val Ser Ala Gly Phe Ser Asn 145 150 155 160 Ser Asn Ser Ser Thr Val Ala Ile Asp His Ser Leu Ser Leu Ala Gly 165 170 175 Glu Arg Thr Trp Ala Glu Thr Met Gly Leu Asn Thr Ala Asp Thr Ala 180 185 190 Arg Leu Asn Ala Asn Ile Arg Tyr Val Asn Thr Gly Thr Ala Pro Ile 195 200 205 Tyr Asn Val Leu Pro Thr Thr Ser Leu Val Leu Gly Lys Asn Gln Thr 210 215 220 Leu Ala Thr Ile Lys Ala Lys Glu Asn Gln Leu Ser Gln Ile Leu Ala 225 230 235 240 Pro Asn Asn Tyr Tyr Pro Ser Lys Asn Leu Ala Pro Ile Ala Leu Asn 245 250 255 Ala Gln Asp Asp Phe Ser Ser Thr Pro Ile Thr Met Asn Tyr Asn Gln 260 265 270 Phe Leu Glu Leu Glu Lys Thr Lys Gln Leu Arg Leu Asp Thr Asp Gln 275 280 285 Val Tyr Gly Asn Ile Ala Thr Tyr Asn Phe Glu Asn Gly Arg Val Arg 290 295 300 Val Asp Thr Gly Ser Asn Trp Ser Glu Val Leu Pro Gln Ile Gln Glu 305 310 315 320 Thr Thr Ala Arg Ile Ile Phe Asn Gly Lys Asp Leu Asn Leu Val Glu 325 330 335 Arg Arg Ile Ala Ala Val Asn Pro Ser Asp Pro Leu Glu Thr Thr Lys 340 345 350 Pro Asp Met Thr Leu Lys Glu Ala Leu Lys Ile Ala Phe Gly Phe Asn 355 360 365 Glu Pro Asn Gly Asn Leu Gln Tyr Gln Gly Lys Asp Ile Thr Glu Phe 370 375 380 Asp Phe Asn Phe Asp Gln Gln Thr Ser Gln Asn Ile Lys Asn Gln Leu 385 390 395 400 Ala Glu Leu Asn Ala Thr Asn Ile Tyr Thr Val Leu Asp Lys Ile Lys 405 410 415 Leu Asn Ala Lys Met Asn Ile Leu Ile Arg Asp Lys Arg Phe His Tyr 420 425 430 Asp Arg Asn Asn Ile Ala Val Gly Ala Asp Glu Ser Val Val Lys Glu 435 440 445 Ala His Arg Glu Val Ile Asn Ser Ser Thr Glu Gly Leu Leu Leu Asn 450 455 460 Ile Asp Lys Asp Ile Arg Lys Ile Leu Ser Gly Tyr Ile Val Glu Ile 465 470 475 480 Glu Asp Thr Glu Gly Leu Lys Glu Val Ile Asn Asp Arg Tyr Asp Met 485 490 495 Leu Asn Ile Ser Ser Leu Arg Gln Asp Gly Lys Thr Phe Ile Asp Phe 500 505 510 Lys Lys Tyr Asn Asp Lys Leu Pro Leu Tyr Ile Ser Asn Pro Asn Tyr 515 520 525 Lys Val Asn Val Tyr Ala Val Thr Lys Glu Asn Thr Ile Ile Asn Pro 530 535 540 Ser Glu Asn Gly Asp Thr Ser Thr Asn Gly Ile Lys Lys Ile Leu Ile 545 550 555 560 Phe Ser Lys Lys Gly Tyr Glu Ile Gly 565 

What is claimed is:
 1. A recombinant DNA construct comprising a Venezuelan Equine Encephalitis virus replicon vector that contains at least one nucleic acid sequence encoding a B. anthracis protein, which sequence is selected from the group consisting of PA, MAT-PA, TPA-PA and PA63, wherein each sequence is operably linked to the 26S promoter.
 2. A recombinant DNA construct according to claim 1 wherein said vector is an expression vector.
 3. A recombinant DNA construct according to claim 1 wherein said vector is a prokaryotic vector.
 4. A recombinant DNA construct according to claim 1 wherein said vector is a eukaryotic vector.
 5. The recombinant DNA construct according to claim 1 wherein said construct is p3014-PA.
 6. The recombinant DNA construct according to claim 1 wherein said construct is p3014-TPA-PA.
 7. The recombinant DNA construct according to claim 1 wherein said construct is p3014-MAT-PA.
 8. The recombinant DNA construct according to claim 1 wherein said construct is p3014-PA63.
 9. A host cell transformed in vitro with a recombinant DNA construct according to claim
 1. 10. A host cell according to claim 9 wherein said host cell is prokaryotic.
 11. A host cell according to claim 9 wherein said host cell is eukaryotic.
 12. Self replicating RNA produced from a construct chosen from the group consisting of: p3014-PA, p3014-TPA-PA, p3014-MAT-PA, and p3014-P63.
 13. Infectious alphavirus particles produced from packaging the self replicating RNA of claim
 12. 14. A pharmaceutical-composition comprising infectious alphavirus particles according to claim 13 in an effective immunogenic amount in a pharmaceutically acceptable carrier and/or adjuvant.
 15. A vaccine for anthrax comprising infectious viral particles containing Venezuelan Equine Encephalitis replicon RNA encoding at least one B. anthracis PA protein selected from the group consisting of PA, PA-MAT, TPA-PA, and PA63, which infectious viral particles when administered to a mouse stimulate a protective immune response against subsequent anthrax challenge.
 16. A composition comprising one or more recombinant DNA constructs chosen from the group consisting of p3014-PA, p3014-TPA-PA, p3014-MAT-PA, and p3014-P63, in a carrier, an adjuvant, or both a carrier and adjuvant.
 17. A method of stimulating a protective immune response against anthrax in a mammal, comprising the step of administering to a mammal a composition comprising infectious viral particles containing VEE replicon RNA encoding a B. anthracis PA protein or peptide fragment thereof, which infectious viral particles stimulate a protective immune response against subsequent anthrax challenge.
 18. The method according to claim 17, wherein the PA protein is selected from the group consisting of PA, PA-MAT, TPA-PA, and PA63.
 19. A pharmaceutical composition comprising infectious viral particles infectious viral particles containing Venezuelan Equine Encephalitis replicon RNA encoding a B. anthracis PA protein, which when administered to a mouse stimulates a protective immune response against subsequent anthrax challenge. 